The Collaborative International Dictionary of English v.0.48:

Cockade \Cock*ade"\, n. [F. cocarble, fr. coquard vain, OF.
   coquart, fr. coq cock, prob. of imitative origin. The
   ornament is so named from its resemblance to the crest of a
   cock. Cf. Coquette.]
   A badge, usually in the form of a rosette, or knot, and
   generally worn upon the hat; -- used as an indication of
   military or naval service, or party allegiance, and in
   England as a part of the livery to indicate that the wearer
   is the servant of a military or naval officer.
   [1913 Webster]

         Seduced by military liveries and cockades. --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

cockade
    n 1: an ornament (such as a knot of ribbon or a rosette) usually
         worn on the hat